The GIF is the animation. It should be around 208KB in size. If you open it in an image viewing program it might only show as a still picture, but in a browser it should play as an animation. Anyway, just doing a web search for “spinning dancer” brings up tons of blogs with the same animation.
That’s not quite the way science works, though. Anyway, that was just a single paper I picked up but there’s more research on this subject. Here’s a paper that tackles the issue in a bit more depth: Interhemispheric switching mediates perceptual rivalry:
The bottom line seems to be that high level processing is involved in perceptual switching of reversible figures and that this processing is lateralized. However, the popular notion that there are “left-brained” people who are “logical” and “right-brained” people who are “intuitive” is essentially pseudo-scientific pop psychology. The notion that ambiguous figures could be used to predict personality attributes such as introversion-extroversion was somewhat popular among certain psychologists of the first half of the 20th century, but with current knowledge this notion appears based on overly simplistic paradigms.
I have never had any problem “flipping” between two images in a still frame optical illusion of this type, yet with this one I have extreme difficulty making her spin counter clockwise when looking straight at her. I wonder if the addition of the “persistance of vision” illusion on top of the “interhemispheric” illusion creates the difficulty in being able to see both sides of the illusion. Thoughts?
I won’t go to the wall for this, but it’s a shadow, b/c she is backlighted. She is a silhouette.
Were it a reflection, she would be frontlighted.
It’s a bit pedantic, but perhaps a significant distinction here. The illusion only works because she is a backlighted silhouette. If she were a frontlighted dancer, you would be able to tell which leg is extended, and the spin would not be ambiguous. Plus there would be even more focus on her…um…attributes.
I can make myself see her rotating either way - it took a little effort the very first time, now it’s easy.
For the doubters, try this:
-Make a mental note of which way the figure appears to be rotating
-Scroll down in your browser so that you can only see the feet
-With your finger, in the space in front of your monitor, trace out the way it would be if the foot was rotating the other direction - try to keep in time/phase with the movement on the screen
-Look back and forth between your finger and the rotating foot
-Then scroll back up
Clockwise she looks like a dancer, but counter-clockwise she looks like an ice skater. Thus it takes a shift in expectations as well as a shift in visual perception to move back and forth. How this affects the right/left brain theory, I don’t know.
(I was stuck on clockwise for a few minutes until I squinched my eyes while staring directly at it.)
I was convinced it switched on its own but I can now make her switch at will.
A cool effect. Now if we could only turn up the lights on her and see her in the flesh…
Like most here I can force myself to see her spin either direction. With her being back lit though, the shadow of her raised leg doesn’t seem at all correct with her spinning clockwise. That’s nothing others haven’t already said though. Also to follow the pile on… nice tits!
I’m really having difficulty understanding the supposed shadow problem. It looks fine to me in both directions. And it’s not a shadow, it’s a reflection. I see her spinning in the air above a glass surface, or something like that.
I think you’re trying to apply too much realism to the situation by supposing that she’s backlit. Maybe she’s made up of a substance that absorbs every wavelength. As for the reflection, who knows? Maybe the floor reflects wavelength we can’t see and shifts them to wavelengths we can see. There’s not enough logic to the situation to justifying inferring the location of light sources.
:smack: Once again, look at it with a group of people. People will perceive it going in different directions at the exact same time. It is a single animated GIF. It does not “change directions” in any real sense other than in the mind of the perceiver.
True. Trying to analyze what brand of light bulb is being used is way beyond the realm of what makes sense here. The figure is very stylized. Still, the shadow/reflection does not make much sense without calling in some really weird tricks of lighting and projection surface.
The figure is a static 3D model silhouetted as it spins. The “shadow” is probably just a flip of the same image. The animation is very crude and skips unevenly. I am not even sure that the “jump” the dancer does was intended at all.
It might well be that all these “defects” are indeed needed to create the illusion. That if it was perfectly rendered, we would have enough data to resolve the spin.
Does anyone have a half decent 3D modeling program to recreate the animation?
Of course the “defects” aren’t necessary for the illusion; cover up the shadow or reflection or whatever you want to think of it as; the illusion is still there. Open the animation up in an image viewer and watch it, still frame by still frame; the ambiguity is still there, in every individual frame and in the motion as a whole.
There simply is not enough data in the picture to resolve the matter of which leg is the right and which is the left, what’s moving inwards and what’s moving outwards, etc.
(If anything, the shadow/reflection/whatever seems to lessen the illusion for many people.)